GEO 101 Lecture Notes - Lecture 20: Viscosity, Stratovolcano, Lapilli
27 Mar 2017
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Announcement: midterm grades for 100- and 200-level courses are due today. Based 95% on first exam grade and 5% on attendance (based on quizzes) Does not include lab nor any extra credit earned; you can ask your ta about your lab grade if you want to know. Reminders: midterm exam #2 is next wednesday (03/08, study guide is available on blackboard, review session in-class on monday (03/06, bring questions. From last time: general features of volcanoes. Summit opening, vent, fumaroles: products of eruptions. Lava, pyroclastic material, nu e ardente, lahars: factors controlling volcano shape and explosivity. Lava composition, temperature, volatiles: types of volcanoes. Steep-walled depression at summit formed by collapse. Formation: magma chamber fills and eruptions begins, as eruption proceeds, magma chamber drains and central portion of volcano collapses, the collapsed area becomes the caldera, lava domes. Associated with explosive eruptions: lava tubes. In an insulated tube, lava can flow faster (~50 km/hr) Lava contracts as it cools, opening joints.
